Devices using organic semiconductors may be produced by a more simple process as compared with the process for devices using inorganic semiconductors such as conventional silicon, and further, it is possible to easily alter material properties by changing their molecular structure. Hence, it is considered that there are many possible variations in the material of organic semiconductors and that, further, it is possible for them to accomplish all of the functions or elements which could not be accomplished by the inorganic semiconductors. Recently, studies associated with this have been actively performed. For example, the organic semiconductors may be applicable for flexible electronic devices such as organic solar cells, organic electroluminescence displays, and organic light detectors.
Patterning of organic semiconductors has been carried out by printing techniques so far, but there was a limitation to a fine fabrication in patterning by printing techniques. Therefore, studies to apply the patterning by printing photolithography and etching which have been applied to the inorganic semiconductor such as conventional silicon, even to the patterning of the organic semiconductor, have been performed.
However, the organic semiconductors may have weak solvent resistance and deteriorate a film formed by organic semiconductors other than some alcohol or aqueous solution (hereinafter, called simply an organic semiconductor film). Also, the organic semiconductor film would be deteriorated even by an alkaline developer of 2.38% by mass TMAH (tetramethylammonium hydroxide aqueous solution), leading to deterioration of the electrical characteristics.
For the purpose of preventing deterioration of the organic semiconductor film, there are known various methods for forming a protective film on the organic semiconductor film and performing various patterning (for example, see Patent Literatures 1 to 3).